“That is why we are working closely with crime fighters to snsure that taxpayers know how to avoid it. We urge people with elderly relatives to warn them about this scam and remind them that they should never trust anyone who phones out of the blue and asks them to pay a tax bill.

Chief Executive of Tax Help for Older People, Gary Millner, said: “This is a particularly wicked scam. The feelings of helplessness, violation and embarrassment for victims are immense.”

Anyone who has been called should contact Action Fraud on Instead the fraudsters are trying to defraud householders by claiming that they owe HMRC a large cash sum - but that the purchase of digital vouchers and gift cards can pay the debt. Victims are told to go to a local store and buy the items, including AppleiTunes cards then read out the redemption code to the scammer who has stayed on the phone the whole time.

Worryingly, the crime has been on the rise in recent months and the average financial loss is £1,150 each. It is being s tressed that most victims are over 65. The scam succeeds as the fraudsters often stop to intimidation, claiming that they will involve police or arrange for their victim’s property to be seized.

HMRC’s Director General of Customer Services Angela MacDonald said: “These scammers are very confident, convincing and utterly ruthless. We don’t want anyone to fall prey to them.That is why we are working closely with crime fighters to snsure that taxpayers know how to avoid it. We urge people with elderly relatives to warn them about this scam and remind them that they should never trust anyone who phones out of the blue and asks them to pay a tax bill.

Chief Executive of Tax Help for Older People, Gary Millner, said: “This is a particularly wicked scam. The feelings of violation and embarrassment on behalf of those targeted are immense.”

Anyone who has been contacted by a scammer should put the phone down and and contact Action Fraud on 0300 123 2040.